You Are Here: Management Updates 2003 Archive June 23, 2003

Date: June 23, 2003
Category: Insects
Subject: Armyworms?

Here we go again???

We have had two reports of armyworm caterpillars active in New England in the last two days. While I have not seen any specimens from either location, descriptions from each location match armyworms. Remember the caterpillars are a very dark background color (variously described as black or dark brown or navy blue) with a thin straw-colored stripe along each side of the body. The head capsule is two-toned brown, and looks kind of "honey-combed". Caterpillars may reach about 1.5 inches when full grown and are not chubby like cutworms.

At the risk of causing a "panic", I just want to report what we know so far. We certainly have not had reports of the incredibly heavy populations that were seen in 2001 ("Medusa's hair" was one description), and I suspect outbreaks, if they occur, will be very sporadic.

The first report came from a golf course near Old Lyme, Connecticut. The caterpillars were active on tall native grasses. While I have not seen any specimens, the superintendent at the golf course lived through the infestations in 2001 and I am quite confident the identification is accurate.

The second report came from a homeowner in Marshfield, about half a mile from the coast. Her description matched that above. The good news about the Marshfield site was that they only found two caterpillars in their search, but there was evidence of feeding activity on the lawn - patches nibbled down nearly to the growing point, and a few bare patches as well. Since there were only a couple caterpillars found, I suspect many may have already completed their development and pupated. Just to be on the safe side, turf managers in the eastern part of Massachusetts might want to keep an eye out for heavy moth flights in the next couple weeks.

That is all we know at this point. If any readers find caterpillars they suspect might be armyworms, let us know. Meanwhile if the caterpillars are already an inch long, they probably will be finished feeding within a week and it will not pay to try and treat infested areas. Try to manage the damage by raising the height of cut and - if the rain ever stops - keeping the lawn appropriately watered.

- Submitted by: Dr. Pat Vittum